diff --git a/obs_stopper_base.jscad b/obs_stopper_base.jscad
new file mode 100644
index 0000000..0164343
--- /dev/null
+++ b/obs_stopper_base.jscad
@@ -0,0 +1,128 @@
+const { polygon, cylinder } = require('@jscad/modeling').primitives;
+const { extrudeLinear } = require('@jscad/modeling').extrusions;
+const { translate, rotate } = require('@jscad/modeling').transforms;
+const { intersect, subtract, union } = require('@jscad/modeling').booleans
+
+function stripRounding(pointArray) {
+  return pointArray.map(point => point.slice(0, 2));
+}
+
+function polyRound({ points, factor }) {
+  return polygon({points: stripRounding(points)});
+}
+
+function polyRoundExtrude({points, length, startRadius, endRadius, factor}) {
+  return extrudeLinear({height: length}, polyRound({ points, factor }))
+}
+
+const baseWidth = 32;
+const baseLength = 27;
+const baseHeight = 1;
+
+const ridgeWidth = 5;
+const ridgeHeight = 3;
+
+function ridge() {
+  const length = baseWidth;
+  const offset = [0, 8, baseHeight];
+  
+  const radii = [
+    [0, 0, 0],
+    [length, 0, 0],
+    [length, ridgeWidth, 0],
+    [0, ridgeWidth, 0],
+  ];
+  
+  return translate(
+    offset,
+    polyRoundExtrude({ points: radii, length: ridgeHeight })
+  );
+}
+
+function base() {
+  const radii = [
+    [0, 0, 0],
+    [baseWidth, 0, 0],
+    [baseWidth, baseLength, 0],
+    [0, baseLength, 0],
+  ];
+  return polyRoundExtrude({ points: radii, length: baseHeight });
+}
+
+function ridgeSpace() {
+  const height = 2;
+  const width = ridgeWidth;
+  const length = 12;
+  const offset = [0, 8, baseHeight + ridgeHeight - height];
+  
+  const radii = [
+    [0, 0, 0],
+    [length, 0, 0],
+    [length, width, 0],
+    [0, width, 0],
+  ];
+  
+  return translate(
+    offset,
+    polyRoundExtrude({ points: radii, length: height })
+  );
+}
+
+function hole() {
+  const radius = 5 / 2;
+  const offset = [6, 8 + radius, 0];
+  
+  return translate(
+    offset,
+    cylinder({height: ridgeHeight + baseHeight, radius: radius * 1.1})
+  );
+}
+
+function wingBase() {
+  const height = 1;
+  const width = 5.5;
+  const wingBaseLength = 15.5;
+  const wingEdgeLength = 10;
+  const wingEdgeOffset = 1;
+  const offset = [0, 3, baseHeight];
+  
+  const radii = [
+    [0, 0, 0],
+    [width, wingEdgeOffset, 0],
+    [width, wingEdgeLength + 1, 0],
+    [0, wingBaseLength, 0],
+  ];
+  
+  // FIXME - this piece is not well-shaped
+  const rootRadii = [
+    [-1, 0, 0],
+    [0, 0, 0],
+    [0, wingBaseLength, 0],
+    [-1, wingBaseLength, 0],
+  ];
+  
+  return translate(
+    offset,
+    rotate(
+      [0, -3*Math.PI / 4, 0],
+      union(
+        polyRoundExtrude({ points: radii, length: height }),
+        polyRoundExtrude({ points: rootRadii, length: height })
+      )
+    )
+  );
+}
+
+const main = () => {
+  return subtract(
+    union(
+      base(),
+      ridge(),
+      wingBase()
+    ),
+    ridgeSpace(),
+    hole()
+  );
+}
+
+module.exports = { main }
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